Infective endocarditis mimics ANCA associated glomerulonephritis

Background: Sub-acute bacterial endocarditis (SBE) rarely presents with features of a small vessel vasculitis. Patients with SBE can also develop multiple serological abnormalities including ANCA. In this report, we present a case of infective endocarditis mimicked ANCA associated glomerulonephritis. Case presentation: A 57-year old male with a clinical picture of rapidly progressive renal failure (RPGN) and positive seology for PR3-ANCA (C-ANCA) was referred to our hospital. The renal histology findings were compatible with focal and segmental glomerular necrosis. After receiving corticosteroid therapy, the patient became febrile and his general condition worsened. Cardiac ultrasound echocardiographic study disclosed multiple large vegetations on the aortic valve. After appropriate antibiotic therapy and valvular surgery, the patient’s condition improved and his serum creatinine reached 1.7 mg/d. Conclusion: Misdiagnosis of SBE as ANCA-associated vasculitis and an inappropriate immunosuppressive therapy can have catastrophic consequences.